The message property name or the name of a message header field
on which to sort. Message header field keys start with the letters
"JMS" and ignore the Key Type field. (For better performance, use
message header fields as sorting keys, rather than message
properties.)

Range of Values: The JMS
Property name (including user properties) or message header fields
that can be sorted on are:

The direction (Ascending or Descending) in which this key will
sort messages. Select Ascending for a FIFO (first in,
first out) sort order. Select Descending for a LIFO (last
in, first out) sort order.